Police the OCB worked with colleagues in the South Eastern Regional Organised Crime Unit, Sussex Police and Lancashire Police to arrest five people.
A total of 12 properties were raided and searched in Northern Ireland, Sussex and Lancashire.
Two men aged 39 and 54 were arrested along with two women aged 31 and 48, during searches in Co Fermanagh yesterday.
A fifth man arrested in Sussex was questioned and subsequently released.
Detective Inspector Andy Hamlin of the OCB said: “This proactive operation against organised criminality was made possible because of the cooperation of multiple law enforcement agencies throughout the United Kingdom.”
It is understood investigation centred around a number of serious offences including blackmail, fraud, money laundering and offences under the Serious Crime Act 2007.